Abstract
We introduce and comment on the concept of contextual pseudo identity. A contextual pseudo identity is a soft identity token that is built from both a user's biometric and the context. When it comes to ubiquitous authentication, a contextual pseudo identity promises better security than that offered by traditional biometrics-based identity tokens: the use of context improves the tokens' disposability and renewability, which are two essential properties in the protection of a user's real identity. Our algorithm for generating contextual pseudo identities extends a Fuzzy Embedder so that it accepts both biometric and context-dependent input. We prove that our way of processing the context preserves the security and reliability properties of the Fuzzy Embedder used in our extension. An example shows how a user can utilize contextual pseudo identity to authenticate to and access ubiquitous services.